Semiconductor device and method of fabricating the same

ABSTRACT

A semiconductor device according to an embodiment includes: a semiconductor substrate having a semiconductor element formed on a surface thereof; an interwiring insulating film formed above the semiconductor substrate; a wiring formed in the interwiring insulating film; a first intervia insulating film formed under the interwiring insulating film; a first via formed in the first intervia insulating film and connected to a lower surface of the wiring; a second intervia insulating film formed on the interwiring insulating film; a second via formed in the second intervia insulating film and connected to an upper surface of the wiring; and a CuSiN film formed in at least one of a position between the interwiring insulating film and the first intervia insulating film, and a position between the interwiring insulating film and the second intervia insulating film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2007-099533, filed on Apr. 5, 2007, the entire contents of which are incorporated herein by reference.

BACKGROUND

With enhancement of performance of recent semiconductor devices having multilayer interconnection structures, there has been shown a tendency to use a low-permittivity insulating material in each of an interwiring insulating film and an intervia insulating film. In general, the low-permittivity insulating material has a high void ratio, and thus has a property of readily containing therein moisture. When a lot of moisture is contained in each of the interwiring insulating film and the intervia insulating film, a barrier metal covering wirings and vias may be oxidized by the moisture. When the oxidization of the barrier metal progresses, there is a possibility that even the barrier metal in a bottom surface of the via and the wiring itself covered with the barrier metal are oxidized to impede the electrical conduction, thereby causing deterioration of the electrical characteristics or the like. In particular, since a ratio of a surface area to a volume is larger in the via than in the wiring, a large influence of the oxidation of the barrier metal is exerted on the via.

A semiconductor device in which a plasma silicon oxide film is formed between an interwiring insulating film and an intervia insulating film is known as the related art in this field. This semiconductor device, for example, is disclosed in Japanese Patent KOKAI No. 2000-294634. According to this semiconductor device, it is possible to obtain a large etching selectivity between each of the interwiring insulating film and the intervia insulating film, and the plasma silicon oxide film. Therefore, the plasma silicon oxide film having a film thickness of, for example, several tens of nanometers can be used as an etching stopper.

However, according to the semiconductor device described in Japanese Patent KOKAI No. 2000-294634, since the plasma silicon oxide film has no function of blocking the moisture, there is a probability that the moisture in the interwiring insulating film moves to the intervia insulating film, so that not only the moisture in the intervia insulating film, but also the moisture in the interwiring insulating film promote the oxidation of the barrier metal covering the via. In addition, the plasma silicon oxide film has a large permittivity. Thus, in this case, it is feared to cause an increase in effective permittivity between the wirings.

BRIEF SUMMARY

A semiconductor device according to one embodiment includes: a semiconductor substrate having a semiconductor element formed on a surface thereof; an interwiring insulating film formed above the semiconductor substrate; a wiring formed in the interwiring insulating film; a first intervia insulating film formed under the interwiring insulating film; a first via formed in the first intervia insulating film and connected to a lower surface of the wiring; a second intervia insulating film formed on the interwiring insulating film; a second via formed in the second intervia insulating film and connected to an upper surface of the wiring; and a CuSiN film formed in at least one of a position between the interwiring insulating film and the first intervia insulating film, and a position between the interwiring insulating film and the second intervia insulating film.

A method of fabricating a semiconductor device according to another embodiment includes: forming an intervia insulating film above a semiconductor substrate having a semiconductor element formed on its surface; forming a Cu film on the intervia insulating film, exposing the Cu film to Si-containing gas to form a Cu—Si compound film, and performing nitriding processing for the Cu—Si compound film, thereby forming a CuSiN film; forming an interwiring insulating film on the CuSiN film; forming a via hole in the intervia insulating film, a wiring trench in the interwiring insulating film, and at least one of a via hole and a wiring trench in the CuSiN film, respectively; and forming a via and a wiring in the via hole and the wiring trench, respectively.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross sectional view of a semiconductor device according to a first embodiment;

FIGS. 2A to 2D are respectively cross sectional views showing a method of fabricating the semiconductor device according to the first embodiment;

FIG. 3 is a cross sectional view of a semiconductor device according to a second embodiment;

FIGS. 4A to 4D are respectively cross sectional views showing a method of fabricating the semiconductor device according to the second embodiment;

FIG. 5 is a cross sectional view of a semiconductor device according to a third embodiment;

FIG. 6 is a cross sectional view of a semiconductor device according to a fourth embodiment; and

FIGS. 7A to 7C are respectively cross sectional views showing a method of fabricating the semiconductor device according to the fourth embodiment.

DETAILED DESCRIPTION First Embodiment

FIG. 1 is a cross sectional view of a semiconductor device according to a first embodiment.

A semiconductor device 1 includes a semiconductor substrate (not shown) having a semiconductor element formed on its surface, and a multilayer interconnection structure laminated on the semiconductor substrate. FIG. 1 is a cross sectional view showing a part of the multilayer interconnection structure.

The semiconductor device 1 includes wirings 2 a and 2 b, interwiring insulating films 4 a and 4 b which are formed in the same layers as those of the wirings 2 a and 2 b, respectively, and which are formed between the wirings 2 a and 2 b, and peripheral wirings (not shown), respectively, a via 7 a through which the wirings 2 a and 2 b are electrically connected to each other, a via 7 b through which the wiring 2 b and an upper wiring (not shown) are electrically connected to each other, and intervia insulating films 8 a and 8 b which are formed in the same layers as those of the vias 7 a and 7 b, respectively, and which are formed between the vias 7 a and 7 b, and peripheral vias (not shown), respectively. It is noted that the disposition of the wirings 2 a and 2 b, the vias 7 a and 7 b, and the like are by no means limited to those shown in FIG. 1.

In addition, cap layers 5 a and 5 b are formed on the interwiring insulating films 4 a and 4 b, respectively, and etching stoppers 6 a and 6 b are formed on the wiring 2 a and the cap layer 5 a, and on the wiring 2 b and the cap layer 5 b, respectively. Also, a barrier metal 3 a is formed on a surface including a lower surface and a side surface of the wiring 2 a, a barrier metal 3 b is formed on surfaces including lower surfaces and side surfaces of the wiring 2 b and the via 7 a, and a barrier metal 3 c is formed on a surface including a lower surface and a side surface of the via 7 b.

A CuSiN film 9 is formed between the interwiring insulating film 4 b and the intervia insulating film 8 a, and between the wiring 2 b and the intervia insulating film 8 a.

Each of the wirings 2 a and 2 b, and the vias 7 a and 7 b, for example, is made of Cu.

Each of the barrier metals 3 a, 3 b and 3 c, for example, is made of a metallic material such as Ta, Ti, W, Ru or Co, or a compound of these metallic materials. In addition, the barrier metals 3 a, 3 b and 3 c have a function of preventing metals in the wirings 2 a and 2 b, and the vias 7 a and 7 b from diffusing into the adjacent members such as the interwiring insulating films 4 a and 4 b, and the intervia insulating films 8 a and 8 b.

Each of the intervia insulating films 8 a and 8 b is made of an insulating material such as SiOC, SiO₂, SiOCH or SiOF. In addition, each of the intervia insulating films 8 a and 8 b, for example, has a thickness of about 150 nm.

Each of the interwiring insulating films 4 a and 4 b can be made of the same material as that of each of the intervia insulating films 8 a and 8 b. In addition, each of the interwiring insulating films 4 a and 4 b may be made of an organic insulating material such as polyarylenes or benzoxazole. Also, each of the interwiring insulating films 4 a and 4 b, for example, has a thickness of about 150 nm.

Each of the cap layers 5 a and 5 b is made of an insulating material such as SiO₂, SiC, SiOCH or SiOC. The cap layers 5 a and 5 b are used as stoppers or the like for planarizing processing utilizing a chemical mechanical polishing (CMP) process when the wirings 2 a and 2 b are formed, respectively. In addition, each of the cap layers 5 a and 5 b, for example, has a thickness of about 100 nm. It is noted that in the case where the damage of the interwiring insulating films 4 a and 4 b when the CMP process or the like is carried out is not going to matter as much, the formation of the cap layers 5 a and 5 b may be omitted.

Each of the etching stoppers 6 a and 6 b is made of an insulating metal, such as SiC, SiN or SiCN, having a high etching selectivity with respect to each of the intervia insulating films 8 a and 8 b. The etching stoppers 6 a and 6 b act as stoppers when the upper members, of the wirings 2 a and 2 b, such as the intervia insulating films 8 a and 8 b are etched, respectively. In addition, the etching stoppers 6 a and 6 b prevent the metals in the wirings 2 a and 2 b from diffusing into the upper members, respectively. It is noted that the etching stoppers 6 a and 6 b may be formed only on the upper surfaces of the wirings 2 a and 2 b, respectively. Also, each of the etching stoppers 6 a and 6 b, for example, has a thickness of about 50 nm.

The CuSiN film 9 can block the movement of the moisture between the interwiring insulating film 4 b and the intervia insulating film 8 a because of its property of hardly permeating the moisture. In addition, the CuSiN film 9 has a thickness of 1 to 10 nm. The reason for this is because when the thickness of the CuSiN film 9 is thinner than 1 nm, the effect of blocking the moisture may be reduced, while when the thickness of the CuSiN film 9 is thicker than 10 nm, the effective permittivity between the peripheral wirings may be largely increased.

FIGS. 2A to 2D are respectively cross sectional views showing a method of fabricating the semiconductor device according to the first embodiment.

Firstly, as shown in FIG. 2A, the wiring 2 a having the surface including the lower surface and the side surface covered with the barrier metal 3 a, the interwiring insulating film 4 a, and the cap layer 5 a are formed above the semiconductor substrate (not shown). For example, after the barrier metal 3 a, and a Cu film becoming the wiring 2 a are formed on the interwiring insulating film 4 a having the wiring trench formed therein, and the cap layer 5 a by utilizing a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, and a plating method, respectively, the barrier metal 3 a and the Cu film which are formed outside the wiring trench are removed by performing the CMP, which results in that the lower wiring 2 a is formed and buried in the wiring trench.

Next, as shown in FIG. 2B, the etching stopper 6 a, the intervia insulating film 8 a, the CuSiN film 9, the interwiring insulating film 4 b, and the cap layer 5 b are laminated in order on the wiring 2 a and the cap layer 5 a.

Here, the CuSiN film 9 is formed in processes which will be described below. Firstly, after a Cu film is formed on the intervia insulating film 8 a to have a thickness of about 1 to about 10 nm by utilizing the CVD method or the PVD method, the resulting Cu film is exposed to Si-containing gas such as monosilane (SiH₄) gas, thereby forming a Cu—Si compound film. After that, nitriding processing is performed for the Cu—Si compound film by performing NH₃ plasma radiation or the like, thereby forming the CuSiN film 9. It is noted that the thickness of the CuSiN film 9 can be controlled by changing the conditions of the process described above. In addition, a time and a temperature which are required to perform each of the processes are controlled in the range of 1 to 30 seconds for each process, and in the range of 250 to 450° C. for each process, respectively.

Next, as shown in FIG. 2C, the etching stopper 6 a, the intervia insulating film 8 a, the CuSiN film 9, the interwiring insulating film 4 b, and the cap layer 5 b are processed by, for example, utilizing a photolithography method and a reactive ion etching (RIE) method. As a result, a via hole 11 is formed in the etching stopper 6 a, the intervia insulating film 8 a, and the CuSiN film 9, and also a wiring trench 10 is formed in the interwiring insulating film 4 b and the cap layer 5 b. In this embodiment, the upper surface of the intervia insulating film 8 a can be protected from being damaged by the etching because the CuSiN film 9 is left on the upper surface of the intervia insulating film 8 a.

It is noted that after the wiring trench 10 and the via hole 11 are formed, the inner surfaces of the wiring trench 10 and the via hole 11 which are damaged by the etching may be repaired. When each of the interwiring insulating film 4 b and the intervia insulating film 8 a, for example, is made of a material, such as methylsiloxane, having a siloxane bond as a main skeleton, the repair is carried out by recombining a portion having a defective methyl group owing to the etching with a hydrocarbon group such as a methyl group by using a repairing agent containing organic gas having a silanol group, an organic chemical or the like.

As shown in FIG. 2D, the wiring 2 b and the via 7 a having the respective surfaces including the lower surfaces and the side surfaces covered with the barrier metal 3 b are formed in the wiring trench 10 and the via hole 11, respectively, by utilizing the same method as that in the case of the lower wiring.

Thereafter, the etching stopper 6 b, the via 7 b having the surface including the lower surface and the side surface covered with the barrier metal 3 c, the intervia insulating film 8 b, and the like are formed in the upper layer, thereby forming the semiconductor device 1 shown in FIG. 1.

According to the first embodiment, the formation of the CuSiN film 9 prevents the moisture in the interwiring insulating film 4 b from moving to the intervia insulating film 8 a. This leads to that the oxidation of the barrier metal 3 b covering the surface including the lower surface and the side surface of the via 7 a is prevented from being promoted by the moisture in the interwiring insulating film 4 b.

In addition, it is relatively easy to control the film thickness of the CuSiN film 9. Thus, the CuSiN film 9 can be formed as a super-thin film. The thinness of the film thickness means that the permittivity of the CuSiN film 9 itself hardly exerts an influence on the effective permittivity between the wirings. Note that, according to a simulation, an increase rate of the effective permittivity between the wirings when the CuSiN film 9 having a thickness of 2 nm is formed on the intervia insulating film, for example, in the 32 nm-node interconnect structure is not higher than 1%. Thus, an influence which the CuSiN film 9 exerts on the effective permittivity between the wirings is negligibly small.

In addition, the CuSiN film 9 can have a large etching selectivity with respect to each of the interwiring insulating film 4 b and the intervia insulating film 8 a. Thus, a possibility that the CuSiN film 9 is removed in the phase of formation of the wiring trench 10 and the via hole 11 is small. For this reason, the CuSiN film 9 is formed below the wiring 2 b as well, so that it is possible to suppress the oxidation of the barrier metal 3 b formed on the lower surface of the wiring 2 b due to the moisture in the intervia insulating film 8 a.

Second Embodiment

A semiconductor device according to a second embodiment is different from that of the first embodiment in position where a CuSiN film is formed. A description of the same respects, such as the structures of other members, as those in the first embodiment is omitted here for the sake of simplicity.

FIG. 3 is a cross sectional view of the semiconductor device according to the second embodiment.

The semiconductor device 1 includes the semiconductor substrate (not shown) having the semiconductor element formed on its surface, and a multilayer interconnection structure laminated on the semiconductor substrate. FIG. 3 is a cross sectional view showing a part of the multilayer interconnection structure.

In this embodiment, a CuSiN film 9 b is formed between the interwiring insulating film 4 b and the intervia insulating film 8 a, and also is not formed below the wiring 2 b. In addition, the CuSiN film 9 b is formed between the interwiring insulating film 4 b and an intervia insulating film (not shown) underlying the CuSiN film 9 b.

FIGS. 4A to 4D are respectively cross sectional views showing a method of fabricating the semiconductor device according to the second embodiment.

Firstly, as shown in FIG. 4A, the wiring 2 a having the surface including the lower surface and the side surface covered with the barrier metal 3 a, the CuSiN film 9 a, the interwiring insulating film 4 a, and the cap layer 5 a are formed above the semiconductor substrate (not shown).

Next, as shown in FIG. 4B, the etching stopper 6 a, the intervia insulating film 8 a, the CuSiN film 9 b, the interwiring insulating film 4 b, and the cap layer 5 b are laminated in order on the wiring 2 a and the cap layer 5 a.

Next, as shown in FIG. 4C, the etching stopper 6 a, the intervia insulating film 8 a, the CuSiN film 9 b, the interwiring insulating film 4 b, and the cap layer 5 b are processed in order by, for example, utilizing the photolithography method and the RIE method, thereby forming the wiring trench 10 and the via hole 11. In this embodiment, a portion of the CuSiN film 9 b corresponding to a position where the wiring 2 b is formed is removed. For this reason, a heat treatment is performed after completion of the formation of the wiring trench 10 and the via hole 11, thereby evaporating the moisture in the intervia insulating film 8 a from the upper surface, of the intervia insulating film 8 a, on which no CuSiN film 9 b is formed. As a result, it is possible to reduce a moisture content of the intervia insulating film 8 a. This heat treatment, for example, is performed at 300° C. for 60 seconds. In this embodiment, each of the CuSiN films 9 a and 9 b can be formed in the same processes as those for the CuSiN film 9 in the first embodiment described above.

It is noted that after the wiring trench 10 and the via hole 11 are formed, the inner surfaces of the wiring trench 10 and the via hole 11 which are damaged by the etching may be repaired. When each of the interwiring insulating film 4 b and the intervia insulating film 8 a, for example, is made of a material, such as methylsiloxane, having a siloxane bond as a main skeleton, the repair is carried out by recombining a portion having a defective methyl group owing to the etching with a hydrocarbon group such as a methyl group by using a repairing agent containing organic gas having a silanol group, an organic chemical or the like.

Next, as shown in FIG. 4D, the wiring 2 b and the via 7 a having the respective surfaces including the lower surfaces and the side surfaces covered with the barrier metal 3 b are formed in the wiring trench 10 and the via hole 11, respectively.

Thereafter, the etching stopper 6 b, the via 7 c having the surface including the lower surface and the side surface covered with the barrier metal 3 c, the intervia insulating film 8 b, and the like are formed in the upper layer, thereby forming the semiconductor device 1 shown in FIG. 3.

According to the second embodiment, the formation of the CuSiN film 9 prevents the moisture in the interwiring insulating film 4 b from moving to the intervia insulating film 8 a similarly to the case of the first embodiment. This leads to that the oxidation of the barrier metal 3 b covering the surface including the lower surface and the side surface of the via 7 a is prevented from being promoted by the moisture in the interwiring insulating film 4 b.

In addition, the heat treatment is performed to evaporate the moisture in the intervia insulating film 8 a from the upper interface, of the intervia insulating film 8 a, on which no CuSiN film 9 b is formed. As a result, it is possible to reduce the moisture content of the intervia insulating film 8 a. This leads to suppression of the oxidation of the barrier metal 3 b covering the surface including the lower surface and the side surface of the via 7 a.

Third Embodiment

A semiconductor device according to a third embodiment is different from that of the first embodiment in position where a CuSiN film is formed. A description of the same respects, such as the structures of other members, as those in the first embodiment is omitted here for the sake of simplicity.

FIG. 5 is a cross sectional view of the semiconductor device according to the third embodiment.

The semiconductor device 1 includes the semiconductor substrate (not shown) having the semiconductor element formed on its surface, and a multilayer interconnection structure laminated on the semiconductor substrate. FIG. 5 is a cross sectional view showing a part of the multilayer interconnection structure.

In this embodiment, the CuSiN film 9 is formed between the interwiring insulating film 4 b and the intervia insulating film 8 a, and between the wiring 2 b and the intervia insulating film 8 a. In addition, a CuSiN film 12 a is formed between the cap layer 5 a and the etching stopper 6 a, and between the wiring 2 a and the etching stopper 6 a. Also, a CuSiN film 12 b is formed between the cap layer 5 b and the etching stopper 6 b, and between the wiring 2 b and the etching stopper 6 b. Each of the CuSiN films 12 a and 12 b is formed in the same processes as those for the CuSiN film 9.

It is noted that the CuSiN film 9 may have a shape in which the portion thereof lying below the wiring 2 b is removed similarly to the case of the CuSiN film 9 b in the second embodiment. In addition, a structure may also be adopted such that the CuSiN films 12 a and 12 b are not formed on the wirings 2 a and 2 b, respectively, but are formed only on the cap layers 5 a and 5 b, respectively. In addition, a structure may also be adopted such that the CuSiN film 9 b is not formed, but only CuSiN films 12 a and 12 b are formed.

According to the third embodiment, the CuSiN films 12 a and 9 are formed between the intervia insulating film 8 a and the lower interwiring insulating film 4 a, and between the intervia insulating film 8 a and the upper interwiring insulating film 4 b, respectively, thereby making it possible to prevent the moisture in the upper and lower interwiring insulating films 4 b and 4 a from moving to the intervia insulating film 8 a. This leads to that the oxidation of the barrier metal 3 b covering the surface including the lower surface and the side surface of the via 7 a can be more effectively suppressed. In addition, the oxidation of the barrier metal 3 c covering the surface including the lower surface and the side surface of the via 7 b can be similarly suppressed.

Fourth Embodiment

A semiconductor device according to a fourth embodiment is different from that of the first embodiment in that air gaps are formed in corresponding one of the interwiring insulating films. A description of the same respects, such as the structures of other members, as those in the first embodiment is omitted here for the sake of simplicity.

FIG. 6 is a cross sectional view of the semiconductor device according to the fourth embodiment.

The semiconductor device 1 includes the semiconductor substrate (not shown) having the semiconductor element formed on its surface, and a multilayer interconnection structure laminated on the semiconductor substrate. FIG. 6 is a cross sectional view showing a part of the multilayer interconnection structure.

In this embodiment, each of air gaps 13 is formed in the interwiring insulating film 4 b, the CuSiN film 9, the cap layer 5 b, and the etching stopper 6 b. It is noted that a disposition of the air gaps 13 is by no means limited to that shown in FIG. 6. In addition, each of the air gaps 13 may be formed in the interwiring insulating film 4 a as well.

In addition, the CuSiN film 9 may have a shape in which the portion thereof lying below the wiring 2 b is removed similarly to the case of the CuSiN film 9 b in the second embodiment. Also, similarly to the case of the third embodiment, the CuSiN film 12 a may be formed between the wiring 2 a and the etching stopper 6 a, and between the cap layer 5 a and the etching stopper 6 a, and the CuSiN film 12 b may be formed between the wiring 2 b and the etching stopper 6 b, and between the cap layer 5 b and the etching stopper 6 b, respectively. Or, the CuSiN films 12 a and 12 b may be formed between the cap layer 5 a and the etching stopper 6 a, and between the cap layer 5 b and the etching stopper 6 b, respectively.

FIGS. 7A to 7C are respectively cross sectional views showing a method of fabricating the semiconductor device according to the fourth embodiment.

Firstly, as shown in FIG. 7A, the processes up to the formation of the wiring 2 b shown in FIG. 2D in the first embodiment are performed.

Next, as shown in FIG. 7B, after the etching stopper 6 b is formed, the etching stopper 6 b, the cap layer 5 b, the interwiring insulating film 4 b, and the CuSiN film 9 are processed in order by, for example, utilizing the photolithography method and the RIE method, thereby forming the air gaps 13. It is noted that a heat treatment is performed after completion of the formation of the air gaps 13 to evaporate the moisture in the intervia insulating film 8 a through the air gaps 13, thus making it possible to reduce the moisture content of the intervia insulating film 8 a.

Next, as shown in FIG. 7C, the intervia insulating film 8 b is formed on the etching stopper 6 b so as to cover the air gaps 13.

After that, the via 7 b having the surface including the lower surface and the side surface covered with the barrier metal 3 c is formed in the intervia insulating film 8 b, thereby forming the semiconductor device 1 shown in FIG. 6.

According to the method of fabricating the semiconductor device 1 described in the first embodiment, it is feared that not only the CuSiN film 9, but also the conductive material such as the Cu film are simultaneously formed when the CuSiN film 9 is formed. When such a conductive material is formed on the surface or inside of the CuSiN film 9, it is feared that a leakage current is caused to flow through the wirings. Thus, according to the fourth embodiment, although the partial dividing of the CuSiN film 9 by the formation of the air gaps 13 reduces the effect of suppressing the movement of the moisture, it is possible to prevent the leakage current from being caused to flow through the wirings due to the existence of the conductive material.

In addition, the formation of the air gaps 13 makes it possible to reduce an interwiring capacitance between the wiring 2 b and its peripheral wiring (not shown).

Other Embodiments

It is noted that the present invention is by no means limited to the embodiments described above, and thus various changes can be made without departing from the gist of the invention.

Moreover, the constituent elements of the embodiments described above can be arbitrarily combined with one another without departing from the gist of the invention. 

1. A semiconductor device, comprising: a semiconductor substrate having a semiconductor element formed on a surface thereof; an interwiring insulating film formed above the semiconductor substrate; a wiring formed in the interwiring insulating film; a first intervia insulating film formed under the interwiring insulating film; a first via formed in the first intervia insulating film and connected to a lower surface of the wiring; a second intervia insulating film formed on the interwiring insulating film; a second via formed in the second intervia insulating film and connected to an upper surface of the wiring; and a CuSiN film formed in at least one of a position between the interwiring insulating film and the first intervia insulating film, and a position between the interwiring insulating film and the second intervia insulating film.
 2. The semiconductor device according to claim 1, wherein the CuSiN film is formed in at least one of the position between the interwiring insulating film and the first intervia insulating film and a position between the wiring and the first intervia insulating film, and the position between the interwiring insulating film and the second intervia insulating film and a position between the wiring and the second intervia insulating film.
 3. The semiconductor device according to claim 1, wherein an air gap is formed in the interwiring insulating film and the CuSiN film.
 4. The semiconductor device according to claim 1, wherein the CuSiN film has a thickness of 1 to 10 nm.
 5. The semiconductor device according to claim 1, wherein each of the first and second vias have barrier metals on their surfaces, respectively.
 6. The semiconductor device according to claim 5, wherein the barrier metal contains at least one of Ta, Ti, W, Ru, and Co.
 7. The semiconductor device according to claim 1, wherein the intervia insulating film contains at least one of SiOC, SiO₂, SiOCH, and SiOF.
 8. The semiconductor device according to claim 1, wherein the interwiring insulating film contains at least one of SiOC, SiO₂, SiOCH, SiOF, and an organic insulating material.
 9. The semiconductor device according to claim 1, wherein a cap layer made of an insulating material is formed on the interwiring insulating film.
 10. The semiconductor device according to claim 1, wherein the CuSiN film is also formed between the lower surface of the wiring and the first intervia insulating film.
 11. The semiconductor device according to claim 1, wherein an etching stopper made of an insulating material is formed under the intervia insulating film.
 12. The semiconductor device according to claim 1, wherein the CuSiN film is also formed between the upper surface of the wiring and the second intervia insulating film.
 13. The semiconductor device according to claim 10, wherein the CuSiN film formed in the position between the interwiring insulating film and the first intervia insulating film and the CuSiN film formed between the lower surface of the wiring and the first intervia insulating film have substantially constant thickness.
 14. A method of fabricating a semiconductor device, comprising: forming an intervia insulating film above a semiconductor substrate having a semiconductor element formed on its surface; forming a Cu film on the intervia insulating film, exposing the Cu film to Si-containing gas to form a Cu—Si compound film, and performing nitriding processing for the Cu—Si compound film, thereby forming a CuSiN film; forming an interwiring insulating film on the CuSiN film; forming a via hole in the intervia insulating film, a wiring trench in the interwiring insulating film, and at least one of a via hole and a wiring trench in the CuSiN film, respectively; and forming a via and a wiring in the via hole and the wiring trench, respectively.
 15. The method of fabricating a semiconductor device according to claim 14, further comprising: forming a Cu film on the interwiring insulating film and the wiring, exposing the Cu film to Si-containing gas to form a Cu—Si compound film, and performing nitriding processing for the Cu—Si compound film to form the CuSiN film on the interwiring insulating film and the wiring.
 16. The method of fabricating a semiconductor device according to claim 14, further comprising: processing the interwiring insulating film and the CuSiN film to form air gaps.
 17. The method of fabricating a semiconductor device according to claim 16, further comprising: performing a heat treatment after the air gaps are formed, thereby evaporating moisture in the intervia insulating film through the air gaps.
 18. The method of fabricating a semiconductor device according to claim 14, wherein the nitriding processing for the Cu—Si compound film is performed by performing NH₃ plasma radiation.
 19. The method of fabricating a semiconductor device according to claim 14, wherein after a barrier metal is formed on inner surfaces of the via hole and the wiring trench, the via and the wiring are formed in the via hole and the wiring trench, respectively.
 20. The method of fabricating a semiconductor device according to claim 14, further comprising: repairing etching damage caused in the inner surfaces of the via hole and the wiring trench after the via hole and the wiring trench are formed in the intervia insulating film and the interwiring insulating film, respectively. 